Re: [PATCH 07/10] sched, fair: Optimize find_busiest_queue()

From: Preeti U Murthy
Date: Fri Aug 23 2013 - 04:14:49 EST


Hi Peter,

On 08/19/2013 09:31 PM, Peter Zijlstra wrote:

In the load balancing code, looks to me that
cpumask_copy(cpus, cpu_active_mask) is not updating the env.cpus at all,
before calling find_busiest_group(). Am I missing something?

Should not cpumask_copy() below be before we update the env.cpus parameter?

static int load_balance(int this_cpu, struct rq *this_rq,
struct sched_domain *sd, enum cpu_idle_type idle,
int *balance)
{
int ld_moved, cur_ld_moved, active_balance = 0;
struct sched_group *group;
struct rq *busiest;
unsigned long flags;
struct cpumask *cpus = __get_cpu_var(load_balance_mask);

struct lb_env env = {
.sd = sd,
.dst_cpu = this_cpu,
.dst_rq = this_rq,
.dst_grpmask = sched_group_cpus(sd->groups),
.idle = idle,
.loop_break = sched_nr_migrate_break,
.cpus = cpus,
};

/*
* For NEWLY_IDLE load_balancing, we don't need to consider
* other cpus in our group
*/
if (idle == CPU_NEWLY_IDLE)
env.dst_grpmask = NULL;

cpumask_copy(cpus, cpu_active_mask);

schedstat_inc(sd, lb_count[idle]);
redo:
group = find_busiest_group(&env, balance);

Regards
Preeti U Murthy

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